High-bearing coupling stepped Helmholtz cavity honeycomb sound absorption structure

Abstract

The invention relates to the technical field of acoustic metamaterial structures, in particular to a high-bearing coupling stepped Helmholtz cavity honeycomb sound absorption structure which comprises a plurality of honeycomb structures arranged periodically. A top micro-perforated hole is formed in the center of the top surface of the honeycomb structure, a vertical sound channel is formed in the center of the interior of the honeycomb structure, and a plurality of Helmholtz resonant cavities are formed in the periphery of the interior of the honeycomb structure; the vertical sound channel is communicated with the micro-perforated structure, and the heights of the Helmholtz resonant cavities are distributed according to an arithmetic progression; and the vertical sound channel is communicated with the Helmholtz resonant cavity through a resonant cavity micro-perforated hole. Through collaborative innovation of acoustic topological optimization and mechanical bearing design, the technical paradox that low frequency needs a thick layer and light weight is difficult to bear load of a traditional sound absorption material is broken through, and an innovative solution is provided for cabin acoustic design of aerospace, high-speed rails and other high-end equipment.

Description

Technical Field

[0001] The present application relates to the technical field of acoustic metamaterial structures, and in particular to a high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure. Background Art

[0002] In the field of noise control engineering, the performance optimization of sound-absorbing structures always revolves around acoustic impedance matching and energy dissipation mechanisms. Existing technical solutions can be divided into three typical implementation methods based on their mechanism of action. Their technical characteristics and inherent limitations are analyzed as follows: 1. Porous medium-filled sound absorption structures: These utilize porous materials such as polyurethane foam and glass wool as the sound absorption layer, inducing viscous dissipation through the material's internal tortuous pores. This approach can achieve a sound absorption coefficient (SAC) above 0.6 at frequencies above 800 Hz, but suffers from two fundamental drawbacks. First, at low frequencies (<500 Hz), the sound absorption efficiency drops sharply to below 0.3 due to a mismatch between the viscous boundary layer thickness and the pore size. Second, the porous matrix must maintain open pore connectivity (typically requiring a porosity >70%), resulting in a reduced material density that cannot meet mechanical load-bearing requirements (experimental data indicates compressive strength is generally below 0.5 MPa).

[0003] 2. Micro-perforated plate resonant structure: This technique creates a thin-film resonant absorber by machining submillimeter-level through-holes in a 0.1-1mm thick plate, combined with a back cavity. While this technology can optimize performance at specific frequencies by adjusting the aperture diameter d and perforation ratio p (typical design parameter range: d = 0.2-0.8mm, p = 1%-5%), it is limited by the precision of the perforation process (existing laser micro-perforation process tolerance is ±10μm), making it difficult to achieve a bandwidth exceeding 1 / 3 octave in practical applications. Furthermore, to cover the low-frequency range of 200-800Hz, the required back cavity depth must reach 50-100mm, making the overall structure thickness far beyond the engineering allowable range.

[0004] 3. Helmholtz resonator array: Honeycomb resonant units achieve narrowband sound absorption through neck-cavity coupling. While this solution can achieve a peak sound absorption coefficient exceeding 0.9 at the target frequency (e.g., 315Hz in the patent embodiment), its effective bandwidth (α>0.5) is less than 20Hz. Research has confirmed that when multiple cavities are connected in parallel to expand the frequency band, the acoustic interference effect between the units will cause the sound absorption curve to fluctuate by 10-15dB. Furthermore, traditional neck structures (straight tube and slit types) lack a flow resistance gradient design, making it difficult to achieve continuous impedance matching over a wide frequency band.

[0005] 4. Composite sound absorption structure: micro-perforated plate + porous layer. Although it extends the effective frequency band to 400-1600Hz through multi-mechanism coupling, it has three significant defects: (1) The total thickness of the structure due to the stacking of layers exceeds 60 mm (data from the example), which cannot meet the space restriction requirements in the fields of aviation, high-speed rail, etc. (2) The difference in mechanical properties between the porous filling layer and the rigid resonant cavity (the difference in elastic modulus is up to three orders of magnitude) leads to stress concentration at the structural interface (finite element analysis shows that the local stress reaches 75 MPa); (3) The manufacturing process is complex, requiring the metal resonant cavity and the porous matrix to be processed separately and then bonded and assembled, resulting in an increase in production costs of more than 40%. Summary of the Invention

[0006] In order to overcome the above-mentioned defects, the present application provides a high-load-bearing coupled stepped Helmholtz cavity honeycomb sound absorption structure, comprising a plurality of periodically arranged honeycomb structures; a top micro-perforation is provided at the center of the top surface of the honeycomb structure, a vertical sound channel is provided in the center of the honeycomb structure, and a plurality of Helmholtz resonance cavities are provided around the honeycomb structure; the vertical sound channel is connected to the top micro-perforation, and the heights of each of the Helmholtz resonance cavities are distributed according to an arithmetic progression; the vertical sound channel is connected to the Helmholtz resonance cavity through the resonance cavity micro-perforation.

[0007] Furthermore, the honeycomb structure is a regular hexagon, the side length of a single cell is 8-12 mm, and the total depth of the cavity is 15-20 mm.

[0008] Furthermore, the diameter of the top micro-perforations is 0.5-1.5 mm.

[0009] Furthermore, the vertical sound channel is in the shape of a regular hexagonal prism.

[0010] Furthermore, the height difference between each of the Helmholtz resonant cavities is 1.5-3.0 mm.

[0011] Furthermore, reinforcing ribs are provided between each of the Helmholtz resonance cavities.

[0012] Furthermore, the aperture ratio of the top micro-perforation to the resonance cavity micro-perforation is 1:0.8-1.2.

[0013] Furthermore, the perforation depths of the top micro-perforations and the resonance cavity micro-perforations are 0.5-2.0 mm.

[0014] Furthermore, a reinforcing rib network with a thickness of 0.5-2.0 mm is provided inside the cavity of the honeycomb structure, dividing the single honeycomb structure into 6-12 trapezoidal sub-cavities.

[0015] Furthermore, the honeycomb sound absorbing structure adopts an additive manufacturing process, and a process compensation margin of 0.1-0.3 mm is set.

[0016] The above technical solution of this application has the following advantages: The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure provided in the present application is provided with a top micro-perforation at the center of the top surface of the honeycomb structure, a vertical sound channel is provided in the center of the honeycomb structure, and multiple Helmholtz resonance cavities are provided around the honeycomb structure. The vertical sound channels are connected to the top micro-perforations, and the heights of the various Helmholtz resonance cavities are distributed according to an arithmetic progression. The vertical sound channels are connected to the Helmholtz resonance cavities through the resonance cavity micro-perforations. Through the collaborative innovation of acoustic topology optimization and mechanical load-bearing design, a breakthrough is made in the technical paradox of traditional sound-absorbing materials that "low frequencies require thick layers and light weight is difficult to bear weight", providing an innovative solution for the cabin acoustic design of high-end equipment such as aerospace and high-speed rail. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 This is a schematic diagram of the upper and lower split structure of the overall isometric view of the honeycomb sound absorption structure provided in this application; Figure 2 A schematic diagram of the honeycomb structure provided in this application; Figure 3 A perspective view of a honeycomb structure provided for this application; Figure 4 A vertical cross-sectional view of a honeycomb structure provided for this application; Figure 5 A top perspective view of a honeycomb structure provided for this application.

[0019] Figure numerals: 1. top surface of honeycomb structure; 2. top micro-perforation; 3. Helmholtz resonance cavity; 4. upper resonance cavity micro-perforation; 5. lower resonance cavity micro-perforation; 6. reinforcing rib; 7. vertical sound channel; 8. vertical sound channel side wall; 9. honeycomb structure bottom plate; 10. honeycomb structure side wall. DETAILED DESCRIPTION

[0020] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0021] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0022] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0024] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized.

[0025] Analysis of defects in existing technologies: (1) Traditional micro-perforated structure: There is a low-frequency sound absorption blind spot (sound wave absorption rate below 1000Hz <30%); (2) Helmholtz resonance cavity: The effective sound absorption bandwidth is less than 2 octaves (typical value 200-600 Hz). To achieve sound absorption below 500 Hz, a cavity thickness of more than 40 mm is required, resulting in an increase in surface density to more than 8 kg / m². (3) Conventional composite structure: The lack of systematic acoustic impedance matching design results in obvious troughs in the transition area of ​​multi-band sound absorption peaks (sound absorption coefficient difference > 0.4).

[0026] This application constructs a three-dimensional gradient impedance structure through bionic honeycomb and partition optimization design: (1) Spatial coupling mechanism: impedance matching coupling between graded Helmholtz resonance units and micro-perforated plates (aperture gradient distribution of 0.5-1.5 mm); (2) Mechanical enhancement design: A cross-truss support system is constructed within the unit cell, so that the structure can achieve an in-plane compressive strength of 18 MPa and a shear strength of 6 MPa at a thickness of 20 mm.

[0027] Quantification of the technical effects of this application: (1) Low-frequency breakthrough: Achieve a sound absorption coefficient of >0.8 in the frequency band below 400Hz (measured at α=0.83 at 380Hz); (2) Lightweight index: The surface density is controlled at 4.2kg / m², which is 47% lower than that of traditional porous structures.

[0028] Through the collaborative innovation of acoustic topology optimization and mechanical load-bearing design, this design breaks through the technical paradox of traditional sound-absorbing materials, which require thick layers for low frequencies and are difficult to bear weight due to their light weight. It provides an innovative solution for the cabin acoustic design of high-end equipment such as aerospace and high-speed rail.

[0029] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] like Figures 1 to 5 As shown, an embodiment of the present application provides a high-load coupled stepped Helmholtz cavity honeycomb sound absorption structure, comprising a plurality of periodically arranged honeycomb structures; a top micro-perforation 2 is provided at the center of the top surface 1 of the honeycomb structure, a vertical sound channel 7 is provided in the center of the honeycomb structure, and a plurality of Helmholtz resonance cavities 3 are provided around the honeycomb structure; the vertical sound channel 7 is connected to the top micro-perforation 2, and the heights of the respective Helmholtz resonance cavities 3 are distributed according to an arithmetic progression; the vertical sound channel 7 is connected to the Helmholtz resonance cavities 3 through the resonance cavity micro-perforations (including the upper resonance cavity micro-perforations 4 and the lower resonance cavity micro-perforations 5).

[0031] In some embodiments, the honeycomb structure is a regular hexagon, the side length of a unit cell is 8-12 mm, and the total depth of the cavity is 15-20 mm.

[0032] In some embodiments, the top micro-perforations 2 have a pore diameter of 0.5-1.5 mm.

[0033] In some embodiments, the vertical sound channel 7 is in the shape of a regular hexagonal prism.

[0034] In some embodiments, the height difference between the Helmholtz resonance cavities 3 is 1.5-3.0 mm.

[0035] In some embodiments, reinforcing ribs 6 are provided between the Helmholtz resonance cavities 3 .

[0036] In some embodiments, the aperture ratio of the top micro-perforations 2 to the resonance cavity micro-perforations is 1:0.8-1.2.

[0037] In some embodiments, the top micro-perforations 2 and the resonance cavity micro-perforations have a perforation depth of 0.5-2.0 mm.

[0038] In some embodiments, a reinforcing rib network with a thickness of 0.5-2.0 mm is provided inside the cavity of the honeycomb structure, dividing the single honeycomb structure into 6-12 trapezoidal sub-cavities.

[0039] In some embodiments, the honeycomb sound absorbing structure is manufactured using an additive manufacturing process, with a process compensation margin of 0.1-0.3 mm.

[0040] This sound-absorbing structure adopts an innovative design method of honeycomb and composite resonance cavity. Its technical solution includes the following core elements: (1) Periodic honeycomb matrix architecture A three-dimensional sound absorption system is constructed using a regular hexagonal honeycomb structure as the basic load-bearing unit. The unit cell side length is controlled within the range of 8-12mm, and the total cavity depth is designed to be in the order of 15-20mm. Optimizing the honeycomb wall thickness achieves a coordinated design of structural stiffness and acoustic performance. A micro-perforation structure is installed at the center of the top surface, with a pore diameter controlled between 0.5-1.5mm.

[0041] (2) Composite resonance coupling mechanism An innovative three-stage coupled system consisting of a microperforated plate, a Helmholtz resonator, and a vertical acoustic channel is constructed. After viscous dissipation in the microperforated plate, the acoustic wave propagates through the central hexagonal acoustic channel for acoustic impedance matching, ultimately completing broadband acoustic energy conversion within the Helmholtz resonator.

[0042] (3) Gradient Helmholtz subsystem Each honeycomb unit houses a stepped Helmholtz resonant cavity array, with the cavities arranged in layers via reinforcing ribs with a thickness of 0.5-2.0mm. The height of each cavity layer is distributed according to a gradient, forming a stepped attenuation structure with a height difference of 1.5-3.0mm, achieving multi-cavity resonant coupling.

[0043] Based on the basic solution, performance improvement is achieved through parameter optimization and structural innovation: (1) Multi-scale resonant cavity parameter optimization A layered gradient design strategy is adopted, with the height h of each resonant cavity distributed according to an arithmetic progression, and the gradient variation Δh is controlled within the range of 1.5-3.0mm. Typical design parameters are: h_n = h_0 + (n-1)Δh (n=1,2,...,6) The foundation height h_0 = 1.0-1.5mm, the height difference between layers Δh = 1.5-3.0mm (2) Composite micro-perforation design The top micro-perforations and the resonant cavity micro-perforations use differential aperture designs, with an aperture ratio controlled within the range of 1:0.8-1.2. The perforation depth is optimized to 0.5-2.0mm, and acoustic impedance matching is achieved in specific frequency bands by adjusting the perforation aspect ratio.

[0044] (3) Load-bearing enhanced structure design A network of 0.5-2.0mm thick reinforcing ribs is placed within the honeycomb structure cavity, dividing a single honeycomb unit into 6-12 trapezoidal sub-cavities. The ribs are arranged radially, with the inter-rib angle controlled within a range of 30°-60°. This increases the compressive strength of the structure to 2-3 times that of traditional cavity structures while maintaining acoustic performance.

[0045] (4) Additive manufacturing process adaptation To address the characteristics of the high-temperature fused deposition modeling (FDM) process, a process compensation margin of 0.1-0.3mm is set. The design values ​​of key feature dimensions (such as micropore diameter and rib thickness) must meet Df ≥ 2δ (Df is the design dimension, δ is the printing accuracy), ensuring that the dimensional accuracy of the molded part is controlled within the range of ±0.1-0.2mm.

[0046] This solution achieves macroscale control through periodic expansion of the honeycomb structure, mesoscale frequency band expansion through stepped Helmholtz cavities, and micro-perforated structures for microscale viscous dissipation, ultimately forming a cross-scale, synergistic, broadband sound absorption system. Finite element analysis verified the structural load-bearing capacity, demonstrating a compressive strength of 8-15 MPa, meeting engineering load requirements.

[0047] Based on theoretical calculations, numerical simulations, and experimental verification, the metamaterial's basic unit has been shown to achieve a sound absorption coefficient greater than 0.8 in the 370-450Hz frequency range, while also reducing its resonant frequency by 42% compared to a conventional honeycomb structure of the same size. This improves the honeycomb panel's low- and mid-frequency sound absorption performance while retaining its advantages of lightweight structure and reduced panel thickness (15mm).

[0048] Specifically, poly(ether-ether-ketone) PEEK material was used, with a density of 1300 kg / m^3, a speed of sound of 3420 m / s, and a printing accuracy of ±0.2 mm. Structural samples were prepared using high-temperature fused deposition modeling (FDM) technology. The samples had a diameter of 95 mm and a thickness of 16 mm (microporous plate thickness of 1 mm, cavity depth of 15 mm). To verify the difference in sound absorption performance between the proposed structure and traditional honeycomb structures, the experiment employed a dual-microphone transfer function method using a BSWA model SW4201 impedance tube to measure the sound absorption coefficient of the proposed structure at frequencies between 200 and 1200 Hz.

[0049] Experimental verification and COMSOL simulations show that the average resonant frequency of the proposed structure is below 440 Hz, a 42% reduction compared to conventional honeycomb structures. Furthermore, the proposed structure exhibits an average frequency bandwidth of 80 Hz, with a sound absorption coefficient greater than 0.8. This demonstrates the proposed structure's superior low- and mid-frequency sound absorption performance.

[0050] Those skilled in the art will clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. In addition, the specific names of the functional units and modules are only for the purpose of distinguishing each other and are not used to limit the scope of protection of this application.

[0051] It should be noted that the various embodiments in this specification are described in a progressive manner. Reference can be made to the same or similar parts between the various embodiments. Each embodiment focuses on the differences from other embodiments. This application is not limited to the specific structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and technologies are omitted here.

[0052] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure, characterized in that: The invention comprises a plurality of periodically arranged honeycomb structures; a top micro-perforation is provided at the center of the top surface of the honeycomb structure, a vertical sound channel is provided in the center of the honeycomb structure, and a plurality of Helmholtz resonance cavities are provided around the honeycomb structure; the vertical sound channel is connected to the top micro-perforation, and the heights of the Helmholtz resonance cavities are distributed according to an arithmetic progression; the vertical sound channel is connected to the Helmholtz resonance cavities through the resonance cavity micro-perforations.

2. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The honeycomb structure is a regular hexagon, the side length of a single cell is 8-12 mm, and the total depth of the cavity is 15-20 mm.

3. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The aperture of the top micro-perforation is 0.5-1.5 mm.

4. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The vertical sound channel is in the shape of a regular hexagonal prism.

5. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The height difference between the Helmholtz resonance cavities is 1.5-3.0 mm.

6. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: Reinforcement ribs are arranged between the Helmholtz resonance cavities.

7. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The aperture ratio of the top micro-perforation to the resonance cavity micro-perforation is 1:0.8-1.

2.

8. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The perforation depths of the top micro-perforations and the resonance cavity micro-perforations are 0.5-2.0 mm.

9. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: A reinforcing rib network with a thickness of 0.5-2.0 mm is arranged inside the cavity of the honeycomb structure, dividing the single honeycomb structure into 6-12 trapezoidal sub-cavities.

10. The high-load-bearing coupled stepped Helmholtz cavity honeycomb sound-absorbing structure according to claim 1, characterized in that: The honeycomb sound-absorbing structure adopts an additive manufacturing process, and a process compensation margin of 0.1-0.3 mm is set.

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